1. Field of the Invention
This invention relates to a device for supplying lubricating oil in a transmission mechanism, and in particular, to a lubricating oil supply device for a transmission mechanism in an automatic transmission for a motor vehicle.
2. Description of the Prior Art
A conventional chain transmission mechanism comprises: an input shaft; an output shaft disposed parallel to the input shaft; a first sprocket provided on the input shaft; a second sprocket provided on the output shaft; a chain for interlocking the first sprocket with the second sprocket; and, a transmission mechanism case forming a transmission mechanism chamber for housing the shafts, sprockets and chain. This type of transmission mechanism has been lubricated by stirring up lubricating oil collected in a bottom part of the transmission mechanism chamber by the rotation of the transmission mechanism.
The lubrication systems for such transmission mechanisms do not provide satisfactory lubrication. The amount of the lubricating oil scattered by the stirring increases with the rotational speed of the transmission mechanism, so that the oil level of the lubricating oil collected in the bottom part of the transmission mechanism chamber is lowered at higher speeds, which is apt to cause insufficient lubrication. The only solution known and practiced to avoid this problem, is to increase the amount of the lubricating oil to ensure sufficient lubrication even under high-speed rotation. Accordingly, the oil level becomes so high that the stirring of the lubricating oil itself is apt to cause an increase in the oil temperature and thereby lower transmission efficiency.